In my opinion, a backpack is must since you carry it easily where ever you want. As you said, you are on camping for long duration suitcase would be extremely difficult to carry all the way. I was on similar tour few months back; I carried backpack by Briggs & Riley luggage which was extremely useful. I carried cash, credit cards, required licenses and permits (for camping, hunting, fishing, etc.), waterproof matches and butane lighter, toilet paper, spare batteries and bulb, rain gear, extra clothing, insect repellent. These are some of the essentials which you need to carry.